diff --git a/graph/src/blockchain/types.rs b/graph/src/blockchain/types.rs
index 18d03b390ba..7caac94c246 100644
--- a/graph/src/blockchain/types.rs
+++ b/graph/src/blockchain/types.rs
@@ -159,6 +159,12 @@ impl BlockPtr {
     //
     // workaround for arweave
     pub fn hash_as_h256(&self) -> H256 {
+        let slice = self.hash_slice();
+
+        if slice.is_empty() {
+            return H256::zero();
+        }
+
         H256::from_slice(&self.hash_slice()[..32])
     }